Weigel shakes his head:
Most states give the power of the map to whomever happens to run the legislature. As 2011 began, Democrats only controlled the redistricting process for 47 seats—safe blue turf like Maryland and Illinois, which they squeezed for every possible gain. They had to. Republicans controlled the process for 202 seats. The Democrats had built the Pelosi house in states like Wisconsin, Ohio, Michigan, North Carolina, and Pennsylvania. Then they lost everything, and the other guys got to draw the maps.
“Republicans weren’t thinking ‘Hey, just how do we draw these lines to screw over Democrats?’ ” says John McHenry, a pollster at Resurgent Republic. “It was, ‘How do we make this suburban Philadelphia seat safer for the Republican who just won it?’ The goal wasn’t so much to add seats as it was to hold on to the 2010 gains.”
Earlier commentary on the subject here.